Paid $0.01 (x402, USDC Base): random UUID v4 — idempotency keys and x402 requestKeys on demand; also a canonical low-cost target for testing x402 payment stacks.
This tool declares no required parameters. Add optional parameters from the input schema as needed.
{
"id": 1,
"jsonrpc": "2.0",
"method": "tools/call",
"params": {
"arguments": {},
"name": "gen_uuid"
}
}| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden, and it discloses the single most important trait: this call costs $0.01 via x402 in USDC on Base. That is exactly the kind of information an agent needs before invoking a paid endpoint. It omits the return format and what happens on an unpaid/failed payment, keeping it out of the 5 band.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
A single dense sentence with no filler. Leading with the price rather than the purpose is defensible for a paid tool but slightly buries what the tool produces behind the billing terms.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a zero-parameter, zero-output-schema utility, the description covers purpose, cost, payment rail, and use cases, which is nearly everything an agent needs. The only real gap is the return value (a UUID string), which is implied but not stated.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The tool takes zero parameters, so there is no parameter semantics to explain; the baseline for a parameterless tool is 4. Nothing in the description misleads about inputs.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description names a specific output ('random UUID v4'), which is concretely distinguishable from sibling generators like gen_random, gen_password, and gen_lorem. It never explicitly contrasts itself with those siblings, but 'UUID v4' is a precise enough resource identifier that an agent can select it without opening a schema.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
It gives concrete usage contexts: idempotency keys, x402 requestKeys, and testing x402 payment stacks. That is genuine when-to-use guidance. It stops short of stating when NOT to use it (e.g., when a non-UUID random value is needed, use gen_random), so it falls below the top band.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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